A light path from light source should be controlled according to different lighting functions of an automobile light to form a specific lighting shape. Meanwhile, requirements of the laws and regulations to the brightness of the test points of relevant lighting functions should be satisfied, especially the functions including the fog-light should also form the horizontal shadingshading lines on the ground, which is shown in FIG. 3; And especially the low beam function should also form the shading lines with inflection points on the ground to avoid dazzling the drivers and affecting the traffic safety, which is shown in FIG. 4.
The available optical module that can form the shading line of the low beam with inflection points is required to be comprised of a main low beam unit that can form a shading line with inflection points, and an auxiliary low beam unit that can form the horizontal shading line, which is shown in FIG. 6. However, the optical module is comprised of three units with complicated structure and large space occupied, of which the main low beam module is comprised of a LED light source, a main low beam mirror, a main low beam screen (shield) and a main low beam lens. Light emitted from the LED light source is reflected by the mirror to the main low beam lens, while the main low beam screen (shield) is set the shape of shading line with inflection points. The said shading line is set at the focus of the main low beam lens. The light shape with inflection points required for the low beam is formed with the screen (shield) of the shading line of the main low beam screen (shield), and is exposed to the ground with the amplification of the lens. However, the aforesaid main low beam unit has the following disadvantages: It has a low light efficiency normally 30%-40%, but the rated luminous flux of the available LED light source is about 1300 lumen, so the luminous flux of the aforesaid main low beam unit that is actually exposed to the round is between 300 lumen and 400 lumen. So the aforesaid main low beam unit cannot satisfy the requirement of the luminous flux between 500 lumens and 1000 lumens.
At present, the solution of the available technology is to reduce the range of illumination of the main low beam unit to about 20 degrees range of both sides of the ground in front of the automobile. But in practice, the range of illumination of the low beam is about 40 degrees of the inner side of the automobile, while about 70 degrees of the outer side of the automobile, so the auxiliary low beam unit is required for the supplementary illumination. The auxiliary low beam unit can be comprised of one or two auxiliary low beam modules, which can form the horizontal shading line with about 40 degrees of the inner side and about 70 degrees of the outer side of the automobile. The disadvantage of the auxiliary low beam unit is that it can only form the horizontal shading line, which cannot satisfy the requirement of the shading line of the low beam with inflection points. So the superposition of the two light shapes is required to form the function of the low beam illumination.
Besides, the aforesaid technology has the following problems:                1. The structure forming the horizontal shading line is achieved with a lens in accordance with another lighting unit that is set in the front. The whole structure is complicated with lots of components, and occupies more space;        2. Only a part of the luminosity emitted from the light source of the automobile can be applied by the lens, while the rest is all wasted;        3. The light that is not applied by the lens can also form the stray light, of which the influence should be removed with the shading settings.        